I know you should never mix powders... how about lot #'s of the same powder? I am about to run out of my first pound of Bullseye and purchased another pound. The lot numbers are different and the date of manufacture is a year later. Is it safe to mix different lot numbers of the same powder? BTW loading 45acp.

I believe it is safe. There are thousands of reloaders (including me) who have done this. Liability laws being what they are it's difficult to imagine the margin of error between lots to be so great as to create an unsafe situation.

If you are using maximum loads however, it might be prudent to check for any pressure signs and back off a little if you do.

When my father and I were shooting trap actively I would buy 8-lb cans.

The couple of times those weren't availble, we would get smaller containers, once 8 1-lb. cans (got a price VERY close to the 8-lb. can price).

When we had to get several smaller cans, we would dump all of them into a large plastic tub, mix thoroughly, and repackage in an empty 8-lb. container. We would always put in the last remnants of the previous batch, too.

What you DO have to do when you do this, though, is rework your loading data.

If you're at the low to middle end of the range, you should be OK. But, if you're using a charge that is within 10 to 20 percent of the maximum, DROP BACK to get into the low end and work your way back up.

Different lots, and even different cans, of the same powder can have slightly different burning characteristics.

I would NOT, however, mix new powder with one that was several years old.

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Beware the man with the S&W .357 Mag.
Chances are he knows how to use it.

Well, I don't mix different lots of powders as some have quite different burning rates. I have run into this with IMR-4831. I have one batch that is in the same rate as IMR-4350. I have to use 4350 data, as the IMR-4831 data is too hot.
I would agree, that if you are in the middle or lower range of the loads for your gun, that when the old batch runs out, just continue with what load you were using. If you are at maximum or close to it, drop back a bit and work back up. You won'y use that much powder and handgun loads use very little, and it beats having a possible KABOOM.
Paul B.

I do it all the time. When I'm getting low on a powder, like down to the last 100 - 200 grains I'll buy a new can and mix the last few tablespoons of old into it. They're the same powder, maybe different lots, literally it's just a drop in the bucket. It's pretty rare for the last cartridge, of the last batch, to take the last drop of powder, from the last can. If there's not enough powder to complete the project I'm working on I'm not going to throw it away. I think it's safer to blend in this way at the beginning then to figuratively "switch horses in the middle of the stream" and open a new can halfway thru a loading project. -- Kernel

I blend same type powders as well. But then with the exception of a couple of magnum rifle calibers, all my loads are middle of the road stuff. I usually blend when I am down to about a third of a can powder. Never had a problem. But then, like I say, my loads are midrange. I don't blend when my loadings approach redline.

There is no real 'mixing' of different lot and containers in the hopper anyway. The powder pretty much travels straight down the tube, into the funnel and then the case. I verified this one time by mixing Bullseye and TiteGroup until I could actually see the difference. It mixed about 15 grains(in a Hornady rotary measure) worth until it cleared. I even chrono'd the mixed rounds, and because the 2 powders have allmost the same burn rates and densities, the scatter in velocity was within the normal deviations.

Thanks for all of your collective experience. FYI Here is the response from Alliance:
"There is no reason to actually blend the two powders but you can just
continue on with the new lot. If you are using a powder measure, then pour
the new powder in on top of the old. We do not recommend blending powder
even of the same type; leave the blending to us. Thanks for your interest
in our powder and let me know if you have any additional questions. Have a
nice day."

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